Continuous chewing gum manufacturing process yielding gum with improved flavor perception

ABSTRACT

A method of continuously manufacturing chewing gum with improved flavor perception comprises the steps of adding at least an elastomer and filler into a high-efficiency continuous mixer, and mixing the elastomer and filler together in the continuous mixer; adding a least one ingredient selected from the group consisting of fats, oils, waxes and elastomer plasticizers into the continuous mixer, and mixing said ingredient with the elastomer and filler in the continuous mixer; and adding at least one sweetener and-at least one flavor into the continuous mixer, and mixing said sweetener and flavor with the remaining ingredients to form a chewing gum composition. These steps are performed using a single high-efficiency continuous mixer and wherein the flavor is added at a level lower than that used to make the same chewing gum composition in a batch mixer but the flavor intensity in the chewing gum product is comparable to that of said same chewing gum composition made in a batch mixer.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. applicationSer. No. 08/362,254, filed on Dec. 22, 1994 now U.S. Pat. No. 5,543,160,which in turn is a continuation-in-part of U.S. application Ser. No.08/305,363, filed on Sep. 13, 1994, now abandoned. Both of the foregoingapplications are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a process for making chewing gum thatproduces an improved flavor perception in the gum. More particularly, itrelates to a process for making gum in a continuous mixer with shortmixing times after the addition of flavor.

BACKGROUND OF THE INVENTION

In a conventional chewing gum manufacturing process, a double arm Sigmablade mixer is used to mix chewing gum ingredients. Gum base, bulkingagents such as sugar or sorbitol for sugarless gum, liquids such assyrup or liquid sorbitol, softeners such as glycerin and lecithin, andflavors are mixed about 5-20 minutes to manufacture the gum.

This conventional gum making process, using batch mixing, involves anopen mixer that allows flavor components to be lost by volatization ordegradation, particularly during the relatively long mixing timesrequired to incorporate the flavor into the chewing gum composition.This is true even though flavor is typically added as the lastingredient, and mixed at the minimum temperatures needed for mixing.While most gum flavors, like spearmint, peppermint, cinnamon andwintergreen are subject to volatization, fruit flavors are especiallysusceptible to this problem.

In conventional gum manufacturing, the time at which flavors are addedeffects the flavor release during chewing. For example, a gum mixed withflavor for extended time periods, longer than 5 minutes, will have aslow flavor release. However, this is not practical in the batch processbecause a mixing time of 10 or 15 minutes causes much of the flavor tobe lost. Thus, optimized flavor perception in the final gum product mayhave to be sacrificed for the sake of keeping the level of flavorvolatization and degradation to a minimum.

Conventionally, chewing gum base and chewing gum products have beenmanufactured using separate mixers, different mixing technologies and,often, at different factories. One reason for this is that the optimumconditions for manufacturing gum base, and for manufacturing chewing gumfrom gum base and other ingredients such as sweeteners and flavors, areso different that it has been impractical to integrate both tasks.Chewing gum base manufacture, on the one hand, involves the dispersive(often high shear) mixing of difficult-to-blend ingredients such aselastomer, filler, elastomer plasticizer, base softeners/emulsifiersand, sometimes wax, and typically requires long mixing times. Chewinggum product manufacture, on the other hand, involves combining the gumbase with more delicate ingredients such as product softeners, bulksweeteners, high intensity sweeteners and flavoring agents usingdistributive (generally lower shear) mixing, for shorter periods.

In order to improve the efficiency of gum base and gum productmanufacture, there has been a trend toward the continuous manufacture ofchewing gum bases and products. U.S. Pat. No. 3,995,064, issued toEhrgott et al., discloses the continuous manufacture of gum base using asequence of mixers or a single variable mixer. U.S. Pat. No. 4,459,311,issued to DeTora et al., also discloses the continuous manufacture ofgum base using a sequence of mixers. Other continuous gum basemanufacturing processes are disclosed in European Patent Publication No.0,273,809 (General Foods France) and in French Patent Publication No.2,635,441 (General Foods France).

U.S. Pat. No. 5,045,325, issued to Lesko et al., and U.S. Pat. No.4,555,407, issued to Kramer et al., disclose processes for thecontinuous production of chewing gum products. In each case, however,the gum base is initially prepared separately and is simply added intothe process. U.S. Pat. No. 4,968,511, issued to D'Amelia et al.,discloses a chewing gum product containing certain vinyl polymers whichcan be produced in a direct one-step process not requiring separatemanufacture of gum base. However, the disclosure focuses on batch mixingprocesses not having the efficiency and product consistency achievedwith continuous mixing. Also, the single-step processes are limited tochewing gums containing unconventional bases which lack elastomers andother critical ingredients.

There is a need for a chewing gum manufacturing process that yields agum with improved flavor perception and reduces the amount of flavorcomponents volatized and degraded during the mixing process. Even morebeneficial would be an integrated continuous manufacturing processhaving the ability to combine chewing gum base ingredients and otherchewing gum ingredients in a single continuous mixer in a way thatreduces flavor loss and yields gum with improved flavor perception.

SUMMARY OF THE INVENTION

The present invention is a method for the continuous manufacture of awide variety of chewing gum products using a continuous mixer andyielding a gum with improved flavor perception. Preferably the mixer isa single, high-efficiency mixer which does not require the separatemanufacture of chewing gum base.

In a first aspect, the invention is a method of continuouslymanufacturing chewing gum with improved flavor perception comprising thesteps of:

a) adding at least an elastomer and filler into a high-efficiencycontinuous mixer, and mixing the elastomer and filler together in thecontinuous mixer;

b) adding a least one ingredient selected from the group consisting offats, oils, waxes and elastomer plasticizers into the continuous mixer,and mixing the ingredient with the elastomer and filler in thecontinuous mixer;

c) adding at least one sweetener and at least one flavor into thecontinuous mixer, and mixing the sweetener and flavor with the remainingingredients to form a chewing gum composition; and

d) wherein steps a)-c) are performed using a single high-efficiencycontinuous mixer and wherein the flavor is added at a level lower thanthat used to make the same chewing gum composition in a batch mixer butthe flavor intensity in the chewing gum product is comparable to that ofthe same chewing gum composition made in a batch mixer.

In a second aspect, the invention is a method of continuouslymanufacturing chewing gum with improved flavor perception according to aformula comprising the steps of:

a) adding at least an elastomer and filler into a high-efficiencycontinuous mixer;

b) subjecting at least the elastomer and filler to dispersive mixing inthe continuous mixer;

c) adding at least one sweetener and at least one flavoring agent intothe elastomer and filler in the continuous mixer;

d) subjecting at least the sweetener, flavoring agent, elastomer andfiller to distributive mixing in the continuous mixer, to form a chewinggum product; and

e) continuously discharging the chewing gum product from the mixer,wherein the flavor intensity in the gum product is higher than theflavor intensity of a gum product made from the same formula in a batchprocess.

In a third aspect, the invention is a method of continuouslymanufacturing chewing gum with improved flavor perception comprising thesteps of:

a) adding at least an elastomer and filler into a blade-and-pin mixer,and mixing the elastomer and filler together using blades and pins;

b) adding at least one ingredient selected from the group consisting offats, oils, waxes and elastomer plasticizers into the blade-and-pinmixer, and mixing the at least one ingredient with the elastomer andfiller using blades and pins; and

c) adding at least one sweetener and at least one flavor into theblade-and-pin mixer, and mixing the sweetener and flavor with theremaining ingredients to form a chewing gum product, the flavor beingadded at a point such that the residence time of the chewing gum in themixer after the flavor is added is not greater than about 30 seconds.

In the preferred continuous process, flavors are mixed very quickly in aclosed system. As a result, flavors have a higher impact in the gum,taste stronger, and make gum taste more flavorful. The high-efficiencymixing allows flavors to be added early or late to a closed system for ashort mixing time of 5 seconds or long mixing time of 30 seconds.

Another surprising result was noticed when comparing flavor added byconventional batch mixing and flavor added to extruded gum by continuousprocess. Because of the short mixing time in a closed system, much lessflavor is lost and the flavor intensity is perceived to be much higherin the extruded gum. This allows for a reduced overall flavor level in agum formulation compared to gum made by batch processing.

The foregoing and other advantages of the invention will become furtherapparent from the following detailed description of the presentlypreferred embodiments, read in conjunction with the accompanyingexamples and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial exploded perspective view of a preferred Busshigh-efficiency mixer used to practice the preferred method of theinvention, illustrating a mixing barrel and mixing screw arrangement.

FIG. 2A is a perspective view of an on-screw element used on theupstream side of a restriction ring assembly, in a preferredhigh-efficiency mixer configuration.

FIG. 2B is a perspective view of an on-screw element used on thedownstream side of the restriction ring assembly in a preferredhigh-efficiency mixer configuration.

FIG. 2C is a perspective view of a restriction ring assembly used in apreferred high-efficiency mixer configuration.

FIG. 3 is a perspective view showing the relative positioning of theelements of FIGS. 2A, 2B and 2C in a preferred high-efficiency mixerconfiguration.

FIG. 4 is a perspective view of a low-shear mixing screw element used ina preferred high-efficiency mixer configuration.

FIG. 5 is a perspective view of a high-shear mixing screw element usedin a preferred high-efficiency mixer configuration.

FIG. 6 is a perspective view of a barrel pin element used in a preferredhigh-efficiency mixer configuration.

FIG. 7 is a schematic diagram of a preferred arrangement of mixingbarrel pins and ingredient feed ports used to practice an embodiment ofthe invention.

FIG. 8 is a schematic diagram of a preferred mixing screw configurationused in conjunction with FIG. 7.

FIG. 9 is a schematic diagram of the relative arrangement of theequipment used to practice a presently preferred embodiment of theinvention.

FIG. 10 is a schematic diagram of the presently preferred mixing screwconfiguration used in the arrangement of FIG. 9.

DETAILED DESCRIPTION OF THE DRAWINGS AND PRESENTLY PREFERRED EMBODIMENTS

As used herein, the term "chewing gum" also includes bubble gum and thelike. All percentages are weight percentages unless otherwise specified.

With preferred embodiments of the invention, it has been found thatflavor may be reduced by about 1-20% in the gum formulation and obtain asimilar flavor intensity as would be produced if the gum were made in abatch process. The level of all flavors, such as spearmint, peppermint,cinnamon, wintergreen, and especially fruit flavors, may be reduced.Fruit flavors are particularly sensitive to volatile loss and levels maybe significantly reduced. Analysis of fruit flavored gum samples made bycontinuous high-efficiency mixing and conventional mixing have shownthat a much lower quantity of volatile components in fruit flavors arelost when made by continuous mixing in a high-efficiency mixer than whenmade by conventional processing.

Because the preferred embodiment of the invention uses a high-efficiencymixer known as a blade-and-pin mixer, and utilizes the manufacture ofthe gum base as well as the chewing gum composition in one mixer, thetotal manufacture of chewing gum, using a single continuoushigh-efficiency mixer, without requiring the separate manufacture ofchewing gum base, will first be discussed. This method can beadvantageously performed using a continuous mixer whose mixing screw iscomposed primarily of precisely arranged mixing elements with only aminor fraction of simple conveying elements. A preferred mixer is ablade-and-pin mixer exemplified in FIG. 1. A blade-and-pin mixer uses acombination of selectively configured rotating mixer blades andstationary barrel pins to provide efficient mixing over a relativelyshort distance. A commercially available blade-and-pin mixer is the Busskneader, manufactured by Buss AG in Switzerland, and available from BussAmerica, located in Bloomingdale, Ill.

Referring to FIG. 1, a presently preferred blade-and-pin mixer 100includes a single mixing screw 120 turning inside a barrel 140 which,during use, is generally closed and completely surrounds the mixingscrew 120. The mixing screw 120 includes a generally cylindrical shaft122 and three rows of mixing blades 124 arranged at evenly spacedlocations around the screw shaft 122 (with only two of the rows beingvisible in FIG. 1). The mixing blades 124 protrude radially outward fromthe shaft 122, with each one resembling the blade of an axe.

The mixing barrel 140 includes an inner barrel housing 142 which isgenerally cylindrical when the barrel 140 is closed around the screw 120during operation of the mixer 100. Three rows of stationary pins 144 arearranged at evenly spaced locations around the screw shaft 122, andprotrude radially inward from the barrel housing 142. The pins 144 aregenerally cylindrical in shape, and may have rounded or bevelled ends146.

The mixing screw 120 with blades 124 rotates inside the barrel 140 andis driven by a variable speed motor 201 (FIG. 9). During rotation, themixing screw 120 also moves back and forth in an axial direction,creating a combination of rotational and axial mixing which is highlyefficient. During mixing, the mixing blades 124 continually pass betweenthe stationary pins 144, yet the blades and the pins never touch eachother. Also, the radial edges 126 of the blades 124 never touch thebarrel inner surface 142, and the ends 146 of the pins 144 never touchthe mixing screw shaft 122.

FIGS. 2-6 illustrate various screw elements which can be used toconfigure the mixing screw 120 for optimum use. FIGS. 2A and 2Billustrate on-screw elements 20 and 21 which are used in conjunctionwith a restriction ring assembly. The on-screw elements 20 and 21 eachinclude a cylindrical outer surface 22, a plurality of blades 24projecting outward from the surface 22, and an inner opening 26 with akeyway 28 for receiving and engaging a mixing screw shaft (not shown).The second on-screw element 21 is about twice as long as the firston-screw element 20.

FIG. 2C illustrates a restriction ring assembly 30 used to build backpressure at selected locations along the mixing screw 120. Therestriction ring assembly 30 includes two halves 37 and 39 mounted tothe barrel housing 142, which halves engage during use to form a closedring. The restriction ring assembly 30 includes a circular outer rim 32,an inner ring 34 angled as shown, and an opening 36 in the inner ringwhich receives, but does not touch, the on-screw elements 20 and 21mounted to the screw shaft. Mounting openings 35 in the surface 32 ofboth halves of the restriction ring assembly 30 are used to mount thehalves to the barrel housing 142.

FIG. 3 illustrates the relationship between the restriction ringassembly 30 and the on-screw elements 20 and 21 during operation. Whenthe mixing screw 120 is turning inside the barrel 140, and reciprocatingaxially, the clearances between the on-screw elements 20 and 21 and theinner ring 34 provide the primary means of passage of material from oneside of the restriction ring assembly 30 to the other. The on-screwelement 20 on the upstream side of the restriction ring assemblyincludes a modified blade 27 permitting clearance of the inner ring 34.The other on-screw element 21 is placed generally downstream of therestriction ring assembly 30, and has an end blade (not visible) whichmoves close to and wipes the opposite surface of the inner ring 34.

The clearances between outer surfaces 22 of the on-screw elements 20 and21 and the inner ring 34 of the restriction ring assembly 30, which canvary and preferably are on the order of 1-5 mm, determine to a largeextent how much pressure build-up will occur in the upstream region ofthe restriction ring assembly 30 during operation of the mixer 100. Itshould be noted that the upstream on-screw element 20 has an L/D ofabout 1/3, and the downstream on-screw element 21 has an L/D of about2/3, resulting in a total L/D of about 1.0 for the on-screw elements.The restriction ring assembly 30 has a smaller L/D of about 0.45 whichcoincides with the L/D of the on-screw elements 20 and 21, which engageeach other but do not touch the restriction ring assembly.

FIGS. 4 and 5 illustrate the mixing or "kneading" elements which performmost of the mixing work. The primary difference between the lower shearmixing element 40 of FIG. 4 and the higher shear mixing element 50 ofFIG. 5 is the size of the mixing blades which project outward on themixing elements. In FIG. 5, the higher shear mixing blades 54 whichproject outward from the surface 52 are larger and thicker than thelower shear mixing blades 44 projecting outward from the surface 42 inFIG. 4. For each of the mixing elements 40 and 50, the mixing blades arearranged in three circumferentially-spaced rows, as explained above withrespect to FIG. 1. The use of thicker mixing blades 54 in FIG. 5 meansthat there is less axial distance between the blades and also lessclearance between the blades 54 and the stationary pins 144 as the screw120 rotates and reciprocates axially (FIG. 1). This reduction inclearance causes inherently higher shear in the vicinity of the mixingelements 50.

FIG. 6 illustrates a single stationary pin 144 detached from the barrel140. The pin 144 includes a threaded base 145 which permits attachmentat selected locations along the inner barrel shaft 142. It is alsopossible to configure some of the pins 144 as liquid injection ports byproviding them with hollow center openings.

FIG. 7 is a schematic view showing a preferred barrel configuration,including a preferred arrangement of barrel pins 144. FIG. 8 is acorresponding schematic view illustrating a preferred mixing screwconfiguration. The mixer 200 whose preferred configuration isillustrated in FIGS. 7 and 8 has an overall active mixing L/D of about19.

The mixer 200 includes an initial feed zone 210 and five mixing zones220, 230, 240, 250 and 260. The zones 210, 230, 240, 250 and 260 includefive possible large feed ports 212, 232, 242, 252 and 262, respectively,which can be used to add major (e.g. solid) ingredients to the mixer200. The zones 240 and 260 are also configured with smaller liquidinjection ports 241, 243, 253, 261, 263, 264, 265, 266, 267 and 268which are used to add liquid ingredients. The liquid injection ports241, 243, 253, 261, 263, 264, 265, 266, 267, and 268 include specialbarrel pins 144 formed with hollow centers, as explained above. As such,the positions of the smaller liquid injection ports can readily bechanged. Also, not all of the injection ports need be used during aparticular gum manufacturing operation. In that case, normal barrel pinswill be used at the locations marked in FIG. 7 as a liquid injectionport. Temperature sensors may also be used on some barrel pins 144 tomeasure product temperatures within the mixer.

Referring to FIG. 7, barrel pins 144 are preferably present in most orall of the available locations, in all three rows as shown.

Referring to FIG. 8, one preferred configuration of the mixing screw 120for some chewing gum products is schematically illustrated as follows,zone 210, which is the initial feed zone, is configured with about 11/3L/D of low shear elements, such as the element 40 shown in FIG. 4. TheL/D of the initial feed zone 210 is not counted as part of the overallactive mixing L/D of 19, discussed above, because its purpose is merelyto convey ingredients into the mixing zones.

The first mixing zone 220 is configured, from left to right (FIG. 8),with two low shear mixing elements 40 (FIG. 4) followed by two highshear elements 50 (FIG. 5). The two low shear mixing elements contributeabout 11/3 L/D of mixing, and the two high shear mixing elementscontribute about 11/3 L/D of mixing. Zone 220 has a total mixing L/D ofabout 3.0, including the end part covered by a 57 mm restriction ringassembly 30 with cooperating on-screw elements 20 and 21 (not separatelydesignated in FIG. 8).

The restriction ring assembly 30 with cooperating on-screw elements 20and 21, straddling the end of the first mixing zone 220 and the start ofthe second mixing zone 230, have a combined L/D of about 1.0, part ofwhich is in the second mixing zone 230. Then, zone 230 is configured,from left to right, with three low shear mixing elements 40 and 1.5 highshear mixing elements 50. The three low shear mixing elements contributeabout 2.0 L/D of mixing, and the 1.5 high shear mixing elementscontribute about 1.0 L/D of mixing. Zone 230 has a total mixing L/D ofabout 4.0.

Straddling the end of the second mixing zone 230 and the start of thethird mixing zone 240 is a 60 mm restriction ring assembly 30 withcooperating on-screw elements 20 and 21 having an L/D of about 1.0.Then, zone 240 is configured, from left to right, with 4.5 high shearmixing elements 50 contributing a mixing L/D of about 3.0. Zone 240 alsohas a total mixing L/D of about 4.0.

Straddling the end of the third mixing zone 240 and the start of thefourth mixing zone 250 is another 60 mm restriction ring assembly 30with cooperating on-screw elements having an L/D of about 1.0. Then, theremainder of the fourth mixing zone 250 and the fifth mixing zone 260are configured with eleven low shear mixing elements 40 contributing amixing L/D of about 71/3. Zone 250 has a total mixing L/D of about 4.0,and zone 260 has a total mixing L/D of about 4.0.

Before explaining where the various chewing gum ingredients are added tothe continuous mixer 200, and how they are mixed, it is helpful todiscuss the composition of typical chewing gums that can be made usingthe method of the invention. A chewing gum generally includes a watersoluble bulk portion, a water insoluble chewing gum base portion, andone or more flavoring agents. The water soluble portion dissipates overa period of time during chewing. The gum base portion is retained in themouth throughout the chewing process.

The insoluble gum base generally includes elastomers, elastomerplasticizers (resins), fats, oils, waxes, softeners and inorganicfillers. The elastomers may include polyisobutylene,isobutylene-isoprene copolymer, styrene butadiene copolymer and naturallatexes such as chicle. The resins may include polyvinyl acetate andterpene resins. Low molecular weight polyvinyl acetate is a preferredresin. Fats and oils may include animal fats such as lard and tallow,vegetable oils such as soybean and cottonseed oils, hydrogenated andpartially hydrogenated vegetable oils, and cocoa butter. Commonly usedwaxes include petroleum waxes such as paraffin and microcrystalline wax,natural waxes such as beeswax, candellia, carnauba and polyethylene wax.

The gum base typically also includes a filler component such as calciumcarbonate, magnesium carbonate, talc, dicalcium phosphate and the like;softeners, including glycerol monostearate and glycerol triacetate; andoptional ingredients such as antioxidants, color and emulsifiers. Thegum base constitutes between 5-95% by weight of the chewing gumcomposition, more typically 10-50% by weight of the chewing gum, andmost commonly 20-30% by weight of the chewing gum.

The water soluble portion of the chewing gum may include softeners, bulksweeteners, high intensity sweeteners, flavoring agents and combinationsthereof. Softeners are added to the chewing gum in order to optimize thechewability and mouth feel of the gum.

The water soluble portion of the chewing gum may include softeners, bulksweeteners, high intensity sweeteners, flavoring agents and combinationsthereof. Softeners are added to the chewing gum in order to optimize thechewability and mouth feel of the gum. The softeners, which are alsoknown as plasticizers or plasticizing agents, generally constitutebetween about 0.5-15% by weight of the chewing gum. The softeners mayinclude glycerin, lecithin, and combinations thereof. Aqueous sweetenersolutions such as those containing sorbitol, hydrogenated starchhydrolysates, corn syrup and combinations thereof, may also be used assofteners and binding agents in chewing gum.

Bulk sweeteners constitute between 5-95% by weight of the chewing gum,more typically 20-80% by weight of the chewing gum and most commonly30-60% by weight of the chewing gum. Bulk sweeteners may include bothsugar and sugarless sweeteners and components. Sugar sweeteners mayinclude saccharide containing components including but not limited tosucrose, dextrose, maltose, dextrin, dried invert sugar, fructose,levulose, galactose, corn syrup solids, and the like, alone or incombination. Sugarless sweeteners include components with sweeteningcharacteristics but are devoid of the commonly known sugars. Sugarlesssweeteners include but are not limited to sugar alcohols such assorbitol, mannitol, xylitol, hydrogenated starch hydrolysates, maltitol,and the like, alone or in combination.

High intensity sweeteners may also be present and are commonly used withsugarless sweeteners. When used, high intensity sweeteners typicallyconstitute between 0.001-5% by weight of the chewing gum, preferablybetween 0.01-1% by weight of the chewing gum. Typically, high intensitysweeteners are at least 20 times sweeter than sucrose. These may includebut are not limited to sucralose, aspartame, salts of acesulfame,alitame, saccharin and its salts, cyclamic acid and its salts,glycyrrhizin, dihydrochalcones, thaumatin, monellin, and the like, aloneor in combination.

Combinations of sugar and/or sugarless sweeteners may be used in chewinggum. The sweetener may also function in the chewing gum in whole or inpart as a water soluble bulking agent. Additionally, the softener mayprovide additional sweetness such as with aqueous sugar or alditolsolutions.

Flavor should generally be present in the chewing gum in an amountwithin the range of about 0.1-15% by weight of the chewing gum,preferably between about 0.2-5% by weight of the chewing gum, mostpreferably between about 0.5-3% by weight of the chewing gum. Flavoringagents may include essential oils, synthetic flavors or mixtures thereofincluding but not limited to oils derived from plants and fruits such ascitrus oils, fruit essences, peppermint oil, spearmint oil, other mintoils, clove oil, oil of wintergreen, anise and the like. Artificialflavoring agents and components may also be used in the flavoringredient of the invention. Natural and artificial flavoring agents maybe combined in any sensorially acceptable fashion.

Optional ingredients such as colors, emulsifiers, pharmaceutical agentsand additional flavoring agents may also be included in chewing gum.

In the preferred embodiments of the invention, the gum base and ultimatechewing gum product are made continuously in the same mixer. Generally,the gum base portion is made using a mixing L/D of about 25 or less,preferably about 20 or less, most preferably about 15 or less. Then, theremaining chewing gum ingredients, including the rework, are combinedwith the gum base to make a chewing gum product using a mixing L/D ofabout 15 or less, preferably about 10 or less, most preferably about 5or less. The mixing of the gum base ingredients and the remainingchewing gum ingredients may occur in different parts of the same mixeror may overlap.

When the preferred blade-and-pin mixer is used, having the configurationdescribed above, the total chewing gum can be made using a mixing L/D ofabout 19. The gum base can be made using an L/D of about 15 or less, andthe remaining gum ingredients can be combined with the gum base using afurther L/D of about 5 or less.

In order to accomplish the total chewing gum manufacture using thepreferred blade-and-pin mixer 200 (FIG. 1), it is advantageous tomaintain the rpm of the mixing screw 120 at less than about 150,preferably less than about 100. Also, the mixer temperature ispreferably optimized so that the gum base is at about 130° F. or lowerwhen it initially meets the other chewing gum ingredients, and thechewing gum product is at about 130° F. or lower (preferably 125° F. orlower) when it exits the mixer. This temperature optimization can beaccomplished, in part, by selectively heating and/or water cooling thebarrel sections surrounding the mixing zones 220, 230, 240, 250 and 260(FIG. 7).

In order to manufacture the gum base, the following procedure can befollowed. The elastomer, filler, and at least some of the elastomersolvent are added to the first large feed port 212 in the feed zone 210of the mixer 200, and are subjected to highly dispersive mixing in thefirst mixing zone 220 while being conveyed in the direction of the arrow122. The remaining elastomer solvent (if any) and polyvinyl acetate areadded to the second large feed port 232 in the second mixing zone 230,and the ingredients are subjected to a more distributive mixing in theremainder of the mixing zone 230.

Fats, oils, waxes (if used), emulsifiers and, optionally, colors andantioxidants, are added to the liquid injection ports 241 and 243 in thethird mixing zone 240, and the ingredients are subjected to distributivemixing in the mixing zone 240 while being conveyed in the direction ofthe arrow 122. At this point, the gum base manufacture should becomplete, and the gum base should leave the third mixing zone 240 as asubstantially homogeneous, lump-free compound with a uniform color.

The fourth mixing zone 250 is used primarily to cool the gum base,although minor ingredient addition may be accomplished. Then, tomanufacture the final chewing gum product, glycerin, corn syrup, otherbulk sugar sweeteners, rework gum, high intensity sweeteners, andflavors can be added to the fifth mixing zone 260, and the ingredientsare subjected to distributive mixing. If the gum product is to besugarless, hydrogenated starch hydrolyzate or sorbitol solution can besubstituted for the corn syrup and powdered alditols can be substitutedfor the sugars.

Glycerin may be added to the first liquid injection port 261 in thefifth mixing zone 260. Solid ingredients (bulk sweeteners, encapsulatedhigh intensity sweeteners, etc.) are added to the large feed port 262.Syrups (corn syrup, hydrogenated starch hydrolyzate, sorbitol solution,etc.) are added to the next liquid injection port 263, and flavors areadded to the final liquid injection port 264. Flavors can alternativelybe added at ports 261 and 263 in order to help plasticize. the gum base,thereby reducing the temperature and torque on the screw. This maypermit running of the mixer at higher rpm and throughput.

The effect of adding flavor very late in the continuous process, such asat injection port 264, is to obtain a gum product having a very fastflavor release, short duration, and high initial impact. The flavor ispreferably mixed only about 5-10 seconds in the gum, compared toconventional gum manufacturing where flavor is mixed about 5 minutes.The effect of adding flavor a little earlier in the continuous process,such as at injection port 263, is to obtain a gum product having aslower flavor release, longer duration and mild flavor impact.

The gum ingredients are compounded to a homogeneous mass which isdischarged from the mixer as a continuous stream or "rope". Thecontinuous stream or rope can be deposited onto a moving conveyor andcarried to a forming station, where the gum is shaped into the desiredform such as by pressing it into sheets, scoring, and cutting intosticks. Because the entire gum manufacturing process is integrated intoa single continuous mixer, there is less variation in the product, andthe product is cleaner and more stable due to its simplified mechanicaland thermal histories.

Testing The Suitability Of A Continuous Mixer

The following preliminary test can be employed to determine whether aparticular continuous mixer with a particular configuration meets therequirements of a high-efficiency mixer suitable for practicing thepreferred method of the invention.

A dry blend of 35.7% butyl rubber (98.5% isobutylene--1.5% isoprenecopolymer, with a molecular weight of 120,000-150,000, manufactured byPolysar, Ltd. of Sarnia, Ontario, Canada as POLYSAR Butyl 101-3); 35.7%calcium carbonate (VICRON 15--15 from Pfizer, Inc., New York, N.Y.);14.3% polyterpene resin (ZONAREZ 90 from Arizona Chemical Company ofPanama City, Fla.) and 14.3% of a second polyterpene resin (ZONAREZ 7125from Arizona Chemical Company) is fed into the continuous mixer inquestion equipped with the mixer configuration to be tested. Thetemperature profile is optimized for the best mixing, subject to therestriction that the exit temperature of the mixture does not exceed170° C. (and preferably remains below 160° C.) to prevent thermaldegradation. In order to qualify as a suitable high-efficiency mixer,the mixer should produce a substantially homogeneous, lump-free compoundwith a uniform milky color in not more than about 10 L/D, preferably notmore than about 7 L/D, most preferably not more than about 5 L/D.

To thoroughly check for lumps, the finished rubber compound may bestretched and observed visually, or compressed in a hydraulic press andobserved, or melted on a hot plate, or made into a finished gum basewhich is then tested for lumps using conventional methods.

Also, the mixer must preferably have sufficient length to complete themanufacture of the gum base, and of the chewing gum product, in a singlemixer, using a total mixing L/D of not more than about 40. Any mixerwhich meets these requirements falls within the definition of ahigh-efficiency mixer suitable for practicing the preferred method ofthe invention.

EXAMPLES

All of the examples were made using the following gum formula:

    ______________________________________                                                         %                                                            ______________________________________                                        Base               19.46                                                      Sugar              62.24                                                      45.5° Baume Corn Syrup                                                                    15.57                                                      Glycerin           1.05                                                       Color              0.29                                                       Flavor             1.39                                                                          100.00                                                     ______________________________________                                    

Comparative Example A

The foregoing formula was made by a conventional batch mixing process ina 150 gallon double arm sigma blade mixer with a batch weight of 1573pounds. The gum base was compounded and added to the mixer as a premixedbase formulation. The chewing gum when discharged had a temperature of113° F.

Example 1-4

For the Examples below, various heated tanks, feeders and a BUSS bladeand pin mixer with a 100 mm mixer screw diameter were set up as shown inFIGS. 7 and 9. The mixer 200 was set up with five mixing zones having atotal mixing L/D of 19, and an initial conveying zone having an L/D of11/3. No die was used at the end of the mixer, unless indicatedotherwise, and the product mixture exited as a continuous rope.

Liquid ingredients were fed using volumetric pumps from tanks 272, 276,277 and 278 into the large feed ports 212 and smaller liquid injectionports. The pumps were appropriately sized and adjusted to achieve thedesired feed rates.

Dry ingredients were added using gravimetric screw feeders 271, 273, 274and 275 into the large addition ports 212,232 and 262. Again, thefeeders were appropriately sized and adjusted to achieve the desiredfeed rates.

Temperature control was accomplished by circulating fluids throughjackets surrounding each mixing barrel zone and inside the mixing screw.Water cooling was used where temperatures did not exceed 200° F., andoil cooling was used at higher temperatures. Where water cooling wasdesired, tap water (typically at about 57° F.) was used withoutadditional chilling.

Temperatures were recorded for both the fluid and the ingredientmixture. Fluid temperatures were set for each barrel mixing zone(corresponding to zones 220, 230, 240, 250 and 260 in FIGS. 7 and 8),and are reported below as Z1, Z2, Z3, Z4 and Z5, respectively. Fluidtemperatures were also set for the mixing screw 120.

Actual mixture temperatures were recorded by temperature sensors 281,282, 283, 284, 285 and 286 (FIG. 7). These sensors were located near thedownstream end of mixing zones 220, 230, 240 and 250 and at two placesin mixing zone 260. Actual mixture temperatures are influenced by thetemperatures of the circulating fluid, the heat exchange properties ofthe mixture and surrounding barrel, and the mechanical heating from themixing process, and often differ from the set temperatures due to theadditional factors.

All ingredients were added to the continuous mixer at ambienttemperature (about 77° F.) unless otherwise noted.

The screw was configured as follows (FIG. 10):

In the first barrel section, four low shear then two high shear elementshaving a total L/D of 4 were fitted to the screw shaft. Straddling theend of the first section and the beginning of the second was a 57 mmrestriction ring which, along with its on-screw hardware, had a L/D of1.

In the second section, three low shear elements then 11/2 high shearelements having a total L/D of 3 were fitted. Straddling the end of thesecond section and beginning of the third was a 60 mm restriction ring(1 L/D).

In the third section was fitted 41/2 high shear elements (3 L/D). A 60mm restriction ring (1 L/D) straddled the third and fourth sections.

The fourth section was fitted with 5 low shear elements (31/3 L/D).

The fifth section was fitted with two conveyor elements, one adjacent tothe ingredient addition port 262, each having an L/D of 1. This wasfollowed by 3 low shear elements having a total L/D of 2. The totalscrew length was 201/3 L/D.

The zone temperatures (Z₁ -Z₅ in ° F.) were set to 350, 350, 150, 55 and55. The screw was heated to 150° F.

Several premix compositions were prepared to simplify the mixingprocess.

Rubber Blend

Three parts butyl rubber were ground with one part calcium carbonate.32.785% of the ground mixture was dry blended with 51.322% calciumcarbonate and 15.893% glycerol ester of hydrogenated rosin.

Polyvinyl Acetate Blend

48.421% low molecular weight PVAc was dry blended with 11.849% glycerolester of polymerized rosin and 39.730% glycerol ester of hydrogenatedrosin.

Fat Blend

The following ingredients were melted and blended:

    ______________________________________                                        7.992%        Hydrogenated Soybean Oil                                        13.712%       Hydrogenated Cottonseed Oil                                     12.199%       Glycerol Monostearate                                           37.070%       Paraffin Wax                                                    28.851%       Microcrystalline Wax                                            0.176%        BHT                                                             ______________________________________                                    

Corn Syrup/Glycerin Blend

93.710% 45.5° Baume corn syrup was heated and blended with 6.290%glycerin.

Sugar/Color Blend

10% of a glycerin slurry of red lake was mixed with 90% sugar in aHobart mixer. The resulting product was a damp powder which could be fedinto the extruder with a twin screw volumetric feeder.

The feed ports for the mixer are depicted in FIGS. 7 and 9. To the firstport 212 were added the rubber blend (34.67 lbs/hr) from feeder 271 andmolten polyisobutylene (5.80 lbs/hr) from tank 272.

Into the second port 232 was added the polyvinyl acetate blend at 24.98lbs/hr from feeder 273.

The molten fat blend was injected in equal portions from tank 276through two injection pins 241 and 243 in section 240 at a total rate of26.98 lbs/hr.

The heated corn syrup/glycerin blend was injected from tank 277 throughpin 267 located at the beginning of section 260 at a rate of 78.92lbs/hr.

Sugar was added from feeder 275 into port 262 at a rate of 283.15 lbs/hralong with the sugar/color blend from feeder 274 at 13.87 lbs./hr.

Example 1

Cinnamon flavor was injected through pin 264 near the end of section 260at a rate of 6.62 lbs/hr. This produced a total output of approximately475 lbs/hr from the extruder.

With this configuration, it was necessary to operate the screw at 109rpm in order to prevent a backup of sugar in the fifth intake port 262.The finished gum exited at 127° F.

Example 2

Another example was made using the same procedures as Example 1, butwith 5% less flavor. The formulation flavor level was 1.32% cinnamonflavor, compared to 1.39% flavor in Example 1. The final dischargetemperature of the product was 126° F.

Example 3

Another example was made using the same procedures as Example 1, butwith 10% less flavor. The formulation flavor level was 1.25% cinnamonflavor, compared to 1.39% flavor in Example 1. The final dischargetemperature of the product was 125° F.

Example 4

Another example was made using the same procedures as Example 1, butwith 15% less flavor. The formulation flavor level was 1.18% cinnamonflavor, compared to 1.39% flavor in Example 1. The final dischargetemperature of the product was 125° F.

Sensory evaluation of the gums of Examples 1 and 2 vs. the gum ofComparative Example A shows that the gum of Example 1 had a higherflavor impact and hot spicy cinnamon character that was stronger thanthe flavor of the gum of Comparative Example A. Sensory evaluation ofthe gum of Example 2 vs. the gum of Comparative Example A showed thatthe gum of Example 2 had a cleaner, milder cinnamon flavor that was morelike that of the gum of Comparative Example A. This shows that flavorlevels may be reduced using high-efficiency mixing extruders compared toconventional mixers. A further reduction in the flavor may be possible,but a lower flavor level reduces plasticization of the gum base, causingit to be more rubbery and cohesive. Any lower flavor levels used wouldrequire some additional base reformulation work.

It should be appreciated that the methods of the present invention arecapable of being incorporated in the form of a variety of embodiments,only a few of which have been illustrated and described above. Theinvention may be embodied in other forms without departing from itsspirit or essential characteristics. It will be appreciated that theaddition of some other ingredients, process steps, materials orcomponents not specifically included will have an adverse impact on thepresent invention. The best mode of the invention may therefore excludeingredients, process steps, materials or components other than thoselisted above for inclusion or use in the invention. However, thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive, and the scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

We claim:
 1. A method of continuously manufacturing chewing gum withimproved flavor perception comprising the steps of:a) adding at least anelastomer and filler into a high-efficiency continuous mixer, and mixingthe elastomer and filler together in the continuous mixer; b) adding atleast one ingredient selected from the group consisting of fats, oils,waxes and elastomer plasticizers into the continuous mixer, and mixingsaid ingredient with the elastomer and filler in the continuous mixer;and c) adding at least one sweetener and at least one flavor into thecontinuous mixer, and mixing said sweetener and flavor with theremaining ingredients to form a chewing gum composition; d) whereinsteps a)-c) are performed using a single high-efficiency continuousmixer and wherein the flavor is added at a level lower than that used tomake the same chewing gum composition in a batch mixer but the flavorintensity in the chewing gum product is comparable to that of said samechewing gum composition made in a batch mixer.
 2. The method of claim 1wherein the flavor level is about 1% to about 20% lower than that usedin said same chewing gum composition made in a batch mixer.
 3. Themethod of claim 1 wherein the flavor level is about 5% to about 15%lower than that used in said same chewing gum composition made in abatch mixer.
 4. The method of claim 1 wherein the flavor level is about10% lower than that used in said same chewing gum composition made in abatch mixer.
 5. The method of claim 1 wherein the gum composition has aresidence time in the mixer of not more than about 30 seconds after theflavor is added.
 6. The method of claim 1 wherein the gum compositionhas a residence time in the mixer of not more than about 15 secondsafter the flavor is added.
 7. The method of claim 1 wherein the gumcomposition has a residence time of about 5 to about 10 seconds afterthe flavor is added.
 8. The method of claim 1 wherein steps a)-c) areperformed using a mixing L/D of not more than about
 40. 9. The method ofclaim 8 wherein steps a) and b) are performed using a mixing L/D of notmore than about
 25. 10. The method of claim 8 wherein step c) isperformed using a mixing L/D of not more than about
 15. 11. The methodof claim 1 wherein the continuous mixer comprises a blade-and-pin mixer.12. A chewing gum product manufactured according to the method ofclaim
 1. 13. A method of continuously manufacturing chewing gum withimproved flavor perception according to a formula comprising the stepsof:a) adding at least an elastomer and filler into a high-efficiencycontinuous mixer; b) subjecting at least the elastomer and filler todispersive mixing in the continuous mixer; c) adding at least onesweetener and at least one flavoring agent into the elastomer and fillerin the continuous mixer; d) subjecting at least the sweetener, flavoringagent, elastomer and filler to distributive mixing in the continuousmixer, to form a chewing gum product; and e) continuously dischargingthe chewing gum product from the mixer, wherein the flavor intensity inthe gum product is higher than the flavor intensity of a gum productmade from the same formula in a batch process.
 14. The method of claim13 wherein the flavor level in the formula is a level substantiallyequal to the flavor level of a chewing gum formula designed forproduction in a conventional mixer.
 15. The method of claim 13 whereinthe flavor level in the formula is about 1% to about 20% less than theflavor level that would be used if the chewing gum product were to bemade in a conventional batch process and the flavor intensity in theproduct is comparable to the flavor intensity of said product made in aconventional batch process.
 16. The method of claim 13 wherein step a)further comprises adding an elastomer plasticizer including aningredient selected from the group consisting of polyvinyl acetates,terpene resins and mixtures thereof.
 17. The method of claim 13 furthercomprising the steps of adding at least one ingredient selected from thegroup consisting of fats, oils, waxes and mixtures thereof to theelastomer and filler in the continuous mixer, and subjecting said atleast one ingredient to distributive mixing with the elastomer andfiller.
 18. The method of claim 13 wherein the flavoring agent comprisesan ingredient selected from the group consisting of citrus oil, fruitessences, peppermint oil, spearmint oil, other mint oils, clove oil, oilof wintergreen, anise, cinnamon and mixtures thereof.
 19. A chewing gumproduct manufactured according to the method of claim
 13. 20. A methodof continuously manufacturing chewing gum with improved flavorperception comprising the steps of:a) adding at least an elastomer andfiller into a blade-and-pin mixer, and mixing the elastomer and fillertogether using blades and pins; b) adding at least one ingredientselected from the group consisting of fats, oils, waxes and elastomerplasticizers into the blade-and-pin mixer, and mixing said at least oneingredient with the elastomer and filler using blades and pins; and c)adding at least one sweetener and at least one flavor into theblade-and-pin mixer, and mixing said sweetener and flavor with theremaining ingredients to form a chewing gum product, said flavor beingadded at a point such that the residence time of the chewing gum in themixer after the flavor is added is not greater than about 30 seconds.21. The method of claim 20 wherein the blade-and-pin mixer comprisesfirst, second, third, fourth and fifth mixing zones.
 22. The method ofclaim 21 wherein steps a) and b) are substantially performed before thefifth mixing zone.
 23. The method of claim 21 wherein step a) issubstantially performed before the third mixing zone.
 24. The method ofclaim 21 wherein step c) is substantially performed after the thirdmixing zone.
 25. The method of claim 20 wherein the blades are mountedto a mixing screw which rotates at less than about 150 rpm.
 26. Themethod of claim 25 wherein the mixing screw rotates at less than about100 rpm.
 27. The method of claim 20 wherein the mixer includes one ormore points of restriction before step c).
 28. The method of claim 27wherein the one or more points of restriction are created by one or morerestriction rings.
 29. A chewing gum product manufactured according tothe method of claim 20.